Platinum-containing constructions

ABSTRACT

Some embodiments include constructions which have platinum-containing structures. In some embodiments, the constructions may have a planarized surface extending across the platinum-containing structures and across metal oxide. In some embodiments, the constructions may have a planarized surface extending across the platinum-containing structures, across a first material retaining the platinum-containing structures, and across metal oxide liners along sidewalls of the platinum-containing structures and directly between the platinum-containing structures and the first material. Some embodiments include methods of forming platinum-containing structures. In some embodiments, first material is formed across electrically conductive structures, and metal oxide is formed across the first material. Openings are formed to extend through the metal oxide and the first material to the electrically conductive structures. Platinum-containing material is formed within the openings and over the metal oxide. Chemical-mechanical polishing is utilized to form a planarized surface extending across the platinum-containing material and the metal oxide.

RELATED PATENT DATA

This patent resulted from a continuation of U.S. patent application Ser.No. 13/234,498, which was filed Sep. 16, 2011, and which is herebyincorporated herein by reference.

TECHNICAL FIELD

Platinum-containing constructions, and methods of formingplatinum-containing constructions.

BACKGROUND

Platinum may have application for utilization in semiconductorconstructions; and, for instance, may have application in integratedcircuitry and/or micro-electro-mechanical systems (MEMS).

Platinum is a noble metal, and thus non-reactive relative to numerousmaterials commonly utilized in semiconductor constructions. Suchnon-reactivity can be beneficial. For instance, some memory cellsutilize oxygen-containing programmable materials between a pair ofelectrically conductive electrodes (such memory cells may be utilizedin, for example, resistive random-access memory [RRAM]). Unfortunately,the programmable materials can problematically react with many of thecommonly-available conductive materials. However, the utilization ofplatinum in the electrodes can alleviate, or even eliminate, problematicreaction with the programmable materials.

Difficulties are encountered in forming platinum-containing structures,in that the non-reactivity of platinum can make the platinum difficultto pattern. It would be desirable to develop new methods for patterningplatinum-containing structures, and it would be desirable for such newmethods to be suitable for utilization in the fabrication ofsemiconductor constructions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-4 are diagrammatic, cross-sectional views of a constructionillustrating process stages of an example embodiment method.

FIG. 5 is a diagrammatic, cross-sectional view of the construction ofFIG. 1 shown at a process stage subsequent to that of FIG. 3, andalternative to that of FIG. 4.

FIGS. 6-11 are diagrammatic, cross-sectional views of a constructionillustrating process stages of another example embodiment method.

FIGS. 12-14 are diagrammatic, cross-sectional views of a constructionillustrating process stages of another example embodiment method. Theprocess stage of FIG. 12 may follow that of FIG. 7 in some embodiments.

FIG. 15 is a diagrammatic, cross-sectional view of the construction ofFIG. 12 shown at a process stage subsequent to that of FIG. 13, andalternative to that of FIG. 14.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

In some embodiments, platinum-containing material is formed along metaloxide, and subsequently the platinum-containing material is subjected tochemical-mechanical polishing (CMP). The utilization of the metal oxidemay lead to reduced surface roughness across the platinum relative toprocesses which do not utilize the metal oxide. For instance, theutilization of the metal oxide may enable the chemical-mechanicalpolished platinum to have a surface roughness of less than 50 Å (asmeasured as the root mean square roughness by atomic force microscopy),whereas omission of the metal oxide may lead to the chemical-mechanicalpolished platinum having a surface roughness of at least about 100 Å (asmeasured as the root mean square roughness by atomic force microscopy).Also, the utilization of the metal oxide may improve retention of theplatinum-containing material within openings in a semiconductorconstruction as compared to processes which do not utilize the metaloxide.

Any suitable metal oxide may be utilized. The term “metal” is usedherein to refer to traditional metals, and not to semiconductors (forinstance, silicon). In some embodiments, the metal oxide may compriseone or more transition metals; and in some embodiments the metal oxidemay comprise, consist essentially of, or consist of one or more ofaluminum oxide, hafnium oxide, zirconium oxide and titanium oxide.

Example embodiments are described with reference to FIGS. 1-15.

Referring to FIG. 1, a construction 10 comprises an electricallyinsulative material 12 supporting a plurality of electrically conductivestructures 14-17.

The electrically insulative material 12 may comprise any suitablecomposition or combination of compositions, and in some embodiments maycomprise one or more of silicon nitride, silicon dioxide, and any ofvarious doped glasses (for instance, borophosphosilicate glass,phosphosilicate glass, fluorosilicate glass, etc.). The insulativematerial 12 may be supported over a semiconductor base (not shown). Suchbase may comprise, for example, monocrystalline silicon. If theelectrically insulative material is supported by a semiconductor base,the combination of the electrically insulative material 12 and theunderlying semiconductor base may be referred to as a semiconductorsubstrate, or as a portion of a semiconductor substrate. The terms“semiconductive substrate,” “semiconductor construction” and“semiconductor substrate” mean any construction comprisingsemiconductive material, including, but not limited to, bulksemiconductive materials such as a semiconductive wafer (either alone orin assemblies comprising other materials), and semiconductive materiallayers (either alone or in assemblies comprising other materials). Theterm “substrate” refers to any supporting structure, including, but notlimited to, the semiconductor substrates described above. In someembodiments, the insulative material 12 may be over a semiconductorconstruction which comprises a semiconductor base and one or more levelsof integrated circuitry. In such embodiments, the levels of integratedcircuitry may comprise, for example, one or more of refractory metalmaterials, barrier materials, diffusion materials, insulator materials,etc.

The electrically conductive structures 14-17 may be lines extending inand out of the page relative to the cross-sectional view of FIG. 1. Suchlines may correspond to access/sense lines; and may, for example,correspond to wordlines or bitlines in some embodiments.

The electrically conductive structures 14-17 comprise electricallyconductive material 18. Such electrically conductive material maycomprise any suitable composition or combination of compositions; and insome embodiments may comprise, consist essentially of, or consist of oneor more of various metals (for instance, tungsten, titanium, copper,etc.), metal-containing substances (for instance, metal nitride, metalsilicide, metal carbide, etc.) and conductively-doped semiconductormaterials (for instance, conductively-doped silicon, conductively-dopedgermanium, etc.).

A material 20 extends over the conductive structures 14-17, and in someembodiments the material 20 may be referred to as a “first material” todistinguish material 20 from other materials formed subsequently tomaterial 20. The first material 20 may comprise a dielectric material;and in some embodiments may comprise, consist essentially of, or consistof silicon dioxide or silicon nitride.

A metal oxide 22 is formed over the first material 20. The metal oxidemay be a dielectric metal oxide, and may comprise any of the metal oxidecompositions discussed above (for instance, may comprise, consistessentially of, or consist of one or more of aluminum oxide, hafniumoxide, zirconium oxide and titanium oxide). The metal oxide may beformed utilizing any suitable processing; including, for example, one ormore of atomic layer deposition (ALD), physical vapor deposition (PVD)and chemical vapor deposition (CVD). The metal oxide may be less than orequal to about 10 Å thick; and may, for example, have a thickness offrom about 5 Å to about 10 Å,

Although a single homogeneous first material 20 is between the metaloxide and the conductive structures 14-17 in the shown embodiment, inother embodiments there may be multiple materials between the metaloxide and the conductive structures.

The metal oxide 22 and first material 20 together form a stack 24, andin some embodiments such stack may be referred to as a dielectric stack.

Referring to FIG. 2, openings 26-29 are etched through the dielectricstack 24 and to upper surfaces of the conductive structures 14-17,respectively. The openings are shown to have substantially verticalsidewall surfaces. In other embodiments, the openings may have moretapered sidewall surfaces. The verticality of the sidewall surfaces ofthe openings may depend upon, among other things, the aspect ratios ofthe openings, the composition of first material 20, and the chemistryutilized during the etch of such openings.

The openings 26-29 may be formed with any suitable processing. Forinstance, a mask (not shown) may be formed over the top of stack 24 todefine locations of openings 26-29, one or more etches may be utilizedto transfer a pattern from the mask through stack 24 to form theopenings, and then the mask may be removed to leave the constructionshown in FIG. 2. The patterned mask may comprise any suitablecomposition or combination of compositions, and may, for example,comprise photoresist and/or materials fabricated utilizingpitch-multiplication methodologies.

Referring to FIG. 3, platinum-containing material 30 is formed over anupper surface of stack 24, and within the openings 26-29 that extendthrough the stack. The platinum-containing material may comprise,consist essentially of, or consist of platinum; and may be formed withany suitable processing, including, for example, one or more of ALD, CVDand PVD.

Referring to FIG. 4, construction 10 is subjected to CMP to removeplatinum-containing material 30 from over the upper surface of stack 24;and to form platinum-containing structures 32-35 from theplatinum-containing material within openings 26-29. In the shownembodiment, the polishing stops on the metal oxide 22.

The polishing forms the shown planarized surface 37 extending acrossmetal oxide 22 and platinum-containing structures 32-35. In someembodiments, the structures 32-35 may ultimately correspond to bottomelectrodes of memory cells, and in such embodiments the polishing may beconsidered to electrically isolate such electrodes from one another.

The polishing may utilize any suitable polishing slurry. For instance,the polishing may utilize a noble metal polishing slurry, such as, forexample, a slurry referred to as FCN-120™, and available from FujimiCorporation of Tualatin, Oreg.

The polishing may be conducted at any suitable temperature, and in someembodiments may be conducted at about room temperature (about 22° C.).

The platinum-containing structures 32-35 have lateral surfaces 32 a, 33a, 34 a and 35 a, respectively, along lateral peripheries of thestructures; and such lateral surfaces are directly against metal oxide22 and first material 20 in the shown embodiment.

The utilization of metal oxide 22 is found to improve the CMP ofplatinum relative to processes which omit such metal oxide. Theimprovement in the CMP may include one or both of reduced surfaceroughness across the resulting platinum-containing structures 32-35relative to prior art processes, and less pull-out of platinum fromwithin openings 26-29 relative to prior art processes.

A possible mechanism by which the metal oxide leads to improved surfaceroughness across the platinum-containing structures is that the metaloxide has appropriate adhesion relative to platinum to enablemicro-peeling of platinum from the metal oxide during CMP. Themicro-peeling leads to substantially continuous, uniform removal ofplatinum from over the metal oxide; in contrast to prior art processeslacking such metal oxide, in which platinum sometimes peels in largesheets.

A possible mechanism by which the metal oxide leads to less pull-out ofplatinum from within openings 26-29 is that the metal oxide hasappropriate adhesion relative to platinum so that the metal oxide onlateral surfaces 32 a, 33 a, 34 a and 35 a assists in retaining theplatinum-containing structures 32-35 within the openings. Additionally,or alternatively, the metal oxide may alleviate the prior art problem ofhaving platinum peel in large sheets during CMP. It is possible thatsome of the prior art problem with platinum structures pulling out fromopenings is due to the platinum peeling in large sheets during CMP, withplatinum being pulled out of the openings and transferring with thelarge platinum sheets that are removed during prior art platinum CMPprocesses.

The above-discussed mechanisms are provided to assist the reader inunderstanding some aspects of the invention, and are not to limit theclaims that follow except to the extent, if any, that such mechanismsare explicitly recited in the claims.

In some embodiments, it is found that utilizing a metal oxide 22consisting of aluminum oxide may be particularly advantageous forachieving platinum CMP in which the resulting platinum-containingstructures have low surface roughness, and in which few, if any,platinum-containing structures are undesirably pulled out from withinthe openings utilized to pattern such structures.

The planarized surface 37 may have a root mean square roughness acrossthe platinum of less than or equal to about 50 Å. Such low amount ofsurface roughness may be advantageous relative to prior art platinumsurfaces having a higher amount of surface roughness. For instance, theplatinum surface having the low amount of surface roughness may providea better pad for deposition of subsequent materials than would aplatinum surface having a higher amount of surface roughness. In someembodiments, the platinum-containing structures 32-35 are electrodes,and programmable material (not shown) is subsequently formed along theupper surfaces of the platinum-containing structures. In suchembodiments, it may be advantageous to form the programmable materialalong a platinum-containing surface having a low amount of surfaceroughness relative to a platinum-containing surface having a higheramount of surface roughness.

The platinum-containing structures 32-35 are contained within theopenings 26-29, and thus have shapes defined by the shapes of theopenings. The openings 26-29 may have any suitable shapes to definedesired platinum-containing structures. In some example embodiments, theopenings may be trenches utilized to define platinum-containing linesthat extend horizontally into and out of the page relative to thecross-section of FIG. 4, in other example embodiments the openings maybe shaped to define vertically-extending platinum-containinginterconnects relative to the cross-section of FIG. 4, etc. The openings26-29 may have substantially the same shapes as one another in someembodiments; and in other embodiments at least one of the openings mayhave a substantially different shape than at least one other of theopenings.

In the shown embodiment, the openings extend to electrically conductivestructures 14-17. In other example embodiments the openings may notextend to such electrically conductive structures. For instance, in someembodiments the openings may be long trenches utilized to defineplatinum-containing lines. Such trenches may be entirely containedwithin the first material 20, rather than extending through such firstmaterial to electrically conductive structures (although there may beregions along the trenches where the trenches contact electricallyconductive structures to form interconnects between theplatinum-containing lines and other circuitry).

FIG. 5 shows a construction 10 a illustrating an embodiment alternativeto that of FIG. 4. Specifically, the CMP has been conducted for asufficient duration to entirely remove metal oxide 22 (FIG. 4), and tothus form the planarized surface 37 extending across platinum-containingstructures 32-35 and first material 20. Accordingly, the lateralsurfaces 32 a, 33 a, 34 a and 35 a of platinum-containing structures32-35 are only against first material 20 in the embodiment of FIG. 5;rather than being against the first material 20 and the metal oxide 22as occurred in the embodiment of FIG. 4.

Another example embodiment is described with reference to FIGS. 6-11.

Referring to FIG. 6, a construction 10 b comprises the first material 20over the electrically conductive structures 14-17.

Referring to FIG. 7, openings 26-29 are etched through first material 20to the underlying electrically conductive structures 14-17.

Referring to FIG. 8, metal oxide 22 is formed across material 20 andwithin openings 26-29. The metal oxide lines sidewalls and bottoms ofthe openings 26-29, and narrows such openings.

Referring to FIG. 9, the metal oxide 22 is subjected to anisotropicetching which removes the metal oxide from over substantially horizontalsurfaces (specifically, from along the bottoms of openings 26-29, andfrom over the top of first material 20), while leaving the metal oxidealong the substantially vertical surfaces (specifically, along thesidewalls of the openings). The segments of metal oxide 22 remaining atthe processing stage of FIG. 9 form a plurality of liners 50 alongsidewall peripheries of the openings 26-29.

Referring to FIG. 10, platinum-containing material 30 is formed withinopenings 26-29, and directly against the liners 50 of metal oxide 22.

Referring to FIG. 11, construction 10 b is subjected to CMP to formplatinum-containing structures 32-35. The polishing forms the planarizedsurface 37 extending across first material 20, liners 50, andplatinum-containing structures 32-35. In the embodiment of FIG. 11, theliners 50 are directly between the first material 20 and sidewallsurfaces of the platinum-containing structures; and are directly againstthe first material 20 and the sidewall surfaces of theplatinum-containing structures.

Another example embodiment is described with reference to FIGS. 12-14.

Referring to FIG. 12, a construction 10 c is shown at a processing stagesubsequent to that of FIG. 7. The construction 10 c comprises metaloxide 22 formed over first material 20 and within the openings 26-29.The metal oxide lines sidewalls of the openings 26-29, and narrows suchopenings. Unlike the above-discussed embodiment of FIG. 8, the metaloxide lines sidewall peripheries of openings 26-29 but is not along thebottom peripheries of such openings. Metal oxide 22 may be formed toline the sidewall peripheries of the openings and not cover the bottomperipheries of the openings utilizing appropriate deposition conditionsand/or high aspect ratio openings; as will be recognized by persons ofordinary skill in the art. Alternatively, the construction of FIG. 12may be formed by forming the metal oxide to initially line the bottomperipheries of the openings in addition to lining the sidewallperipheries of the openings, and the metal oxide may then be selectivelyremoved from the bottom peripheries of the openings utilizingappropriate etching and patterning; as will be recognized by persons ofordinary skill in the art.

The metal oxide 22 may be considered to form an expanse 52 across anupper surface of first material 20; and specifically across regions ofthe first material between the openings 26-29.

Referring to FIG. 13, platinum-containing material 30 is formed acrossdielectric material 22 and within openings 26-29.

Referring to FIG. 14, construction 10 c is subjected to CMP to formplatinum-containing structures 32-35. The polishing forms the planarizedsurface 37 extending across metal oxide expanse 52, and across theplatinum-containing structures 32-35.

FIG. 15 shows a construction 10 d illustrating an embodiment alternativeto that of FIG. 14. Specifically, the CMP has been conducted for asufficient duration to entirely remove metal oxide 22 from over firstmaterial 20, and to thus form liners 50 from the metal oxide 22. Theplanarized surface 37 formed by the CMP extends acrossplatinum-containing structures 32-35, liners 50 and first material 20.

The particular orientation of the various embodiments in the drawings isfor illustrative purposes only, and the embodiments may be rotatedrelative to the shown orientations in some applications. The descriptionprovided herein, and the claims that follow, pertain to any structuresthat have the described relationships between various features,regardless of whether the structures are in the particular orientationof the drawings, or are rotated relative to such orientation.

The cross-sectional views of the accompanying illustrations only showfeatures within the planes of the cross-sections, and do not showmaterials behind the planes of the cross-sections in order to simplifythe drawings.

When a structure is referred to above as being “on” or “against” anotherstructure, it can be directly on the other structure or interveningstructures may also be present. In contrast, when a structure isreferred to as being “directly on” or “directly against” anotherstructure, there are no intervening structures present. When a structureis referred to as being “connected” or “coupled” to another structure,it can be directly connected or coupled to the other structure, orintervening structures may be present. In contrast, when a structure isreferred to as being “directly connected” or “directly coupled” toanother structure, there are no intervening structures present.

In some embodiments, a construction comprises a dielectric stack havingmetal oxide over a first material. Platinum-containing structuresextending into the dielectric stack, with the platinum-containingstructures having sidewall surfaces along the metal oxide and along thefirst material. A planarized surface extends across theplatinum-containing structures and the metal oxide.

In some embodiments, a construction comprises a first material,platinum-containing structures extending into the first material, andmetal oxide liners along sidewall surfaces of the platinum-containingstructures and directly between said sidewall surfaces and the firstmaterial. A planarized surface extends across the platinum-containingstructures, the first material and the metal oxide liners.

In some embodiments, a method of forming a plurality ofplatinum-containing structures comprises forming a first material acrossa plurality of electrically conductive structures, and forming metaloxide across the first material. Openings are formed to extend throughthe metal oxide and the first material to the electrically conductivestructures. Platinum-containing material is formed within the openingsand over the metal oxide. Chemical-mechanical polishing is utilized toform a planarized surface extending across the platinum-containingmaterial and the metal oxide.

In some embodiments, a method of forming a plurality ofplatinum-containing structures comprises forming a first material acrossa plurality of electrically conductive structures, and forming metaloxide across the first material. Openings are formed to extend throughthe metal oxide and the first material to the electrically conductivestructures. Platinum-containing material is formed within the openingsand over the metal oxide. Chemical-mechanical polishing is utilized toremove the metal oxide and form a planarized surface extending acrossthe platinum-containing material and the first material.

In some embodiments, a method of forming a plurality ofplatinum-containing structures comprises forming a first material acrossa plurality of electrically conductive structures. Openings are formedto extend through the first material to the electrically conductivestructures. Metal oxide is formed across the first material and withinthe openings. The metal oxide within the openings lines sidewalls andbottoms of the openings. The metal oxide is etched to remove the metaloxide from over the first material and from across the bottoms of theopenings while leaving liners of the metal oxide along the sidewalls ofthe openings. Platinum-containing material is formed within the openingsand directly against the metal oxide liners. Chemical-mechanicalpolishing is utilized to form a planarized surface extending across theplatinum-containing material, the first material and the metal oxideliners.

In some embodiments, a method of forming a plurality ofplatinum-containing structures comprises forming a first material acrossa plurality of electrically conductive structures. Openings are formedto extend through the first material to the electrically conductivestructures. Metal oxide is formed across the first material and withinthe openings. The metal oxide lines sidewalls of the openings to narrowthe openings, and the metal oxide forms an expanse across regions of thefirst material between the openings. Platinum-containing material isformed within the narrowed openings and over the metal oxide.Chemical-mechanical polishing is utilized to form a planarized surfaceextending across the platinum-containing material and across the metaloxide expanse.

In some embodiments, a method of forming a plurality ofplatinum-containing structures comprises forming a first material acrossa plurality of electrically conductive structures. Openings are formedto extend through the first material to the electrically conductivestructures. Metal oxide is formed across the first material and withinthe openings. The metal oxide lines sidewalls of the openings to narrowthe openings, and the metal oxide forms an expanse across regions of thefirst material between the openings. Platinum-containing material isformed within the openings and directly over the metal oxide expanse.Chemical-mechanical polishing is utilized to remove the metal oxideexpanse and form a planarized surface extending across theplatinum-containing material, the first material and segments of themetal oxide lining sidewalls of the openings.

In compliance with the statute, the subject matter disclosed herein hasbeen described in language more or less specific as to structural andmethodical features. It is to be understood, however, that the claimsare not limited to the specific features shown and described, since themeans herein disclosed comprise example embodiments. The claims are thusto be afforded full scope as literally worded, and to be appropriatelyinterpreted in accordance with the doctrine of equivalents.

We claim:
 1. A construction, comprising: a dielectric material supportedby a semiconductor substrate; a first opening within the dielectricmaterial; a second opening within the dielectric material, the secondopening being separated from the first opening by a single blockconsisting of the dielectric material, the single block of thedielectric material having a first sidewall of the dielectric materialwithin the first opening and a second sidewall of the dielectricmaterial within the second opening, the single block of the dielectricmaterial having an upper surface consisting of the dielectric materialand extending an entirety of a distance between the first and secondsidewalls; metal oxide liners lining the first and second openings, themetal oxide liners being in direct contact with the first sidewall ofthe dielectric material within the first opening and in direct contactwith the second sidewall of the dielectric material within the secondopening; platinum within the first and second openings, the platinumbeing in direct contact with the metal oxide liners, the platinum andthe metal oxide liners entirely filling the first and second openings;and a planarized surface extending across the platinum, the dielectricmaterial and the metal oxide liners.
 2. The construction of claim 1wherein metal oxide of the metal oxide liners comprises one or moretransition metals.
 3. The construction of claim 1 wherein the metaloxide comprises one or more of aluminum oxide, hafnium oxide, zirconiumoxide and titanium oxide.
 4. The construction of claim 1 wherein themetal oxide consists of aluminum oxide.
 5. The construction of claim 1wherein the dielectric material comprises silicon dioxide.